Drying Apparatus Comprising a Filter

ABSTRACT

A drying apparatus includes an outer case, a portion of the outer case defining a cavity in which articles can be dried, an outlet disposed at the lower end of the cavity and a filter unit arranged downstream of the outlet, wherein the filter unit includes a particulate filter and a sterilising filter. By providing this filter unit including both a particulate filter and a sterilising filter, solid matter and bacteria can be removed from the waste liquid. This results in a hygienic and sanitary waste liquid output from the filter unit.

REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 USC 371 ofInternational Application No. PCT/GB06/004681, filed Dec. 14, 2006,which claims the priority of United Kingdom Application No. 0602075.4,filed Feb. 2, 2006, the contents of both of which prior applications areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to drying apparatus. Particularly, theinvention relates to drying apparatus including a filter unit forremoving particulates and bacteria from a waste liquid such as water.

BACKGROUND OF THE INVENTION

Conventional arrangements for collecting and removing waste water fromdrying apparatus such as hand dryers are well known from, for example,U.S. Pat. No. 5,459,944. Waste water is collected via a duct or similarand transferred to a drip collector for subsequent manual removal. Suchstorage of waste water is unhygienic, may lead to the spread of bacteriaand requires regular maintenance to empty the drip collector andmaintain a sanitary environment.

The addition of an antibacterial water absorption sheet with a largesurface area to encourage evaporation is known from JP 11-18999 A. Thiscounters some of the problems of bacterial infestation and results inless frequent emptying of a water collector. However, particulate matterwill be deposited on the sheet, and this will affect the performance ofthe machine over time and require frequent cleaning.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide drying apparatuswhich is capable of filtering and sterilising liquid more efficientlyand reliably than prior art apparatus.

The invention provides drying apparatus comprising an outer case, aportion of the outer case defining a cavity in which articles can bedried, an outlet disposed at the lower end of the cavity and a filterunit arranged downstream of the outlet, wherein the filter unitcomprises a particulate filter and a sterilising filter. By providing afilter unit comprising a particulate filter and a sterilising filter,solid matter and bacteria can be removed from the waste liquid. Thisresults in a hygienic and sanitary waste liquid output from the filterunit.

Preferably, the sterilising filter is located downstream of theparticulate filter. By this arrangement, the particulate filter canremove some solid material and larger particulates from the waste liquidto prevent the sterilising filter from clogging.

Preferably, the filter unit further comprises flow directing means forguiding liquid through the filter unit. By providing flow directingmeans, the liquid can be directed to flow through the sterilisingfilter. The flow directing means allow efficient use of the sterilisingfilter ensuring that the water leaving the filter unit has beensufficiently treated.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described with reference tothe accompanying drawings, in which:

FIG. 1 a is a perspective view of a hand dryer according to the presentinvention;

FIG. 1 b is a side view of the hand dryer of FIG. 1 a;

FIG. 2 is a section through the hand dryer of FIG. 1 a showing a filterunit;

FIG. 3 is an enlarged version of part of FIG. 2 showing the internalworkings of the hand dryer and the filter unit in greater detail;

FIG. 4 is a perspective view of a liquid treatment module including thefilter unit removed from the hand dryer of FIG. 1 a;

FIG. 5 a is perspective view from above of the hand dryer of FIG. 1 ashowing the liquid treatment module partially removed from the handdryer; and

FIG. 5 b is a perspective view from below of the hand dryer of FIG. 1 ashowing the liquid treatment module partially removed from the handdryer.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 a and 1 b show a hand dryer 10 according to the presentinvention. The hand dryer 10 includes an outer case 12, a front wall 14a, a rear wall 14 b, two side walls 14 c, 14 d and a cavity 16. The rearwall 14 b may include elements suitable for attaching the hand dryer 10to a wall surface or other suitable fixture. Elements for connecting thehand dryer 10 to a power source may also be included.

The cavity 16 is defined by opposing arcuate front and rear walls 16 a,16 b. The cavity 16 is open at its upper end 18, and the dimensions ofthe opening are sufficient to allow a user's hands (not shown) to beinserted easily into the cavity 16 for drying. A high-speed airflow isgenerated by a motor unit having a fan (not shown). The motor unit andfan are located inside the outer case 12. The high-speed airflow isexpelled through two slot-like openings 20 disposed at the upper end 18of the cavity 16 to dry the user's hands. These features are notmaterial to the present invention and will not be described any furtherhere. The cavity 16 is open at the sides as can be seen in FIGS. 1 a and1 b.

As can be seen from FIG. 2, a drain channel 22 is located at the lowerend 24 of the cavity 16. The drain channel 22 is delimited by the loweredges of the front wall 16 a and the rear wall 16 b of the cavity 16 andslopes downwardly towards one side of the cavity 16. An outlet 26 islocated in the drain channel 22. The outlet 26 can take any suitableform. In this embodiment, it comprises a circular aperture with acentral plug 26 a. The outlet 26 and plug 26 a delimit a narrow, annularopening.

Referring to FIGS. 2 and 3, a chamber 40 is formed in a lower part ofthe outer case 12 below the cavity 16. The chamber 40 is delimited by aplurality of chamber walls 40 a and has an open lower end. A liquidtreatment module 30 is located in the chamber 40 and is held in place byclips, quarter turn fastenings or other fastening means (not shown).

Referring to FIGS. 3 and 4, the liquid treatment module 30 includes afilter unit 200. The filter unit 200 is designed to filter particulatesand impurities from the water, and to kill bacteria in the water. Afilter inlet 202 is located at the upper end of the filter unit 200 andcommunicates with the outlet 26. A sump 204 is located downstream of thefilter inlet 202. The sump 204 has a base 204 a. A wall 206 of the sumpforms a weir 206 a. The height of the weir 206 a determines the maximumlevel of liquid that can be contained within the sump 204. A filteroutlet 208 is delimited by the weir 206 a, the wall 206 of the sump 204and the outer walls 210 of the filter unit 200. The filter outlet 208provides an outlet for water flowing over the weir 206 a.

A partition 212 extends from the upper portion of the filter unit 200adjacent the filter inlet 202 into the sump 204. The partition 212extends partially into the sump 204 such that the distal end 212 a ofthe partition 212 is spaced from the base 204 a of the sump 204. Thepartition 212 is arranged such that the volume of a first region 204 bof the sump 204 beneath the filter inlet 202 is greater than a secondregion 204 c of the sump 204 adjacent the weir 206 a.

A sterilising filter 214 is located at the base 204 a of the sump 204.The sterilising filter 214 consists of particles of an iodine-loadedresin. The resin is loaded at a concentration of 500 g/l. In thisembodiment, the volume of the sterilising filter 214 is 50 ml. Theiodine-loaded resin acts as a sterilising compound to kill any bacteriapresent in the water. The particles of the sterilising filter 214 aresubstantially spherical and have dimensions in the range of 0.1 to 2 mm(average particle size 0.8 mm). The sterilising filter 214 isdimensioned such that the distal end 212 a of the partition 212 extendspartially into the sterilising filter 214.

A particulate filter 216 is located above the sterilising filter 214 andcomprises glass beads with diameters of 4 mm. The particulate filter 216is located on top of the sterilising filter 214 in the first region 204b beneath the filter inlet 202 which is bounded by the partition 212 andthe sump 204. The particulate filter 216 has a volume of 10 ml. Further,the particulate filter 216 operates as a pre-filter, preventing largerparticles of solid matter (in particular soap) from blocking thesterilising filter 214. In order to improve performance, the area of thebed of the particulate filter 216 and sterilising filter 214 ismaximised. A large bed area reduces the pressure drop across the filtersand increases the resistance of the filters to fouling and becomingblocked.

Both the sterilising filter 214 and the particulate filter 216 arelocated in the sump 204 below the maximum level of liquid that can becontained in the sump 204. This means that, once the level of liquid inthe sump 204 has reached the maximum, operational, level, thesterilising filter 214 and the particulate filter 216 are completelysubmerged in the water. This is beneficial because the sterilisingfilter 214 is prone to cracking and forming air pockets if it ispermitted to dry out once it has become wetted. By keeping thesterilising filter 214 continuously wetted, this problem is avoided. Inaddition, this configuration ensures that the water flow is welldistributed. Further, the maximum level of liquid should be far enoughabove particulate filter 216 to allow the head of water to applypressure on the bed of the filters.

The liquid treatment module 30 further includes a liquid dispersion unit35 located below the filter unit 200. The liquid dispersion unit 35 isarranged to receive water from the filter outlet 208. An exhaust conduit37 located within the liquid dispersion unit 35 provides a communicationpath from the liquid dispersion unit 35 to the outside of the outer case12 of the hand dryer 10. The liquid dispersion unit 35 further includesa collector 100 for collecting water from the filter outlet 208. Thecollector 100 has a base 100 a. A high frequency agitator in the form ofa piezo-electric device 102 is located at the base 100 a. A fan 104 issupported on one of the chamber walls 40 a. The fan 104 is locatedoutside the chamber 40 separate from the liquid treatment module 30. Thefan 104 is configured to direct an airflow into the collector 100through an aperture 38 provided in the liquid treatment module 30.

In use, the water removed from a user's hands during the drying processflows down the front wall 16 a and the rear wall 16 b of the cavity 16and into the drain channel 22 disposed at the lower end 24 of the cavity16. The drain channel 22 collects and guides the water towards theoutlet 26.

Upon entering the outlet 26, the water passes into the filter unit 200through the filter inlet 202 (see arrow A). The water falls onto theparticulate filter 216 (arrow B) and spreads evenly across the surfaceof the particulate filter 216. As the water moves down through the beadsof the particulate filter 216 under the influence of gravity, largerparticles of dirt and debris will be left behind in the particulatefilter 216. When the water reaches the sterilising filter 214 (arrow C),the majority of the solid particulates in the water will have beenremoved by the particulate filter 216.

The sterilising filter 214 sterilises the water by deactivating bacteriain the water. The iodine-loaded resin releases iodine into the water ata rate of 1 to 5 parts per million (ppm). Iodine is a strong oxidant andhence acts as broad spectrum antimicrobial. The water flows down throughthe sterilising filter 214, is sterilised and is then deposited in thebottom of the sump 204. This process continues and the volume of watercollected in the sump 204 increases until it reaches the maximum levelpermitted by the weir 206 a. Up until this point, the water levelseither side of the partition 212 experience an equal force due toatmospheric pressure. However, if more water is introduced through thefilter inlet 202, the increased head of water in the first region 204 bwill cause an imbalance in the forces acting on the water levels eitherside of the partition 212. The effect of this is for the mass of theadded water to apply a force downwardly on the water in the sump 204.This causes a net movement of water in the direction shown by the arrowD. The partition 212 directs the flow of water down towards the base 204a of the sump 204, down through a part of the sterilising filter 214located in the first region 204 b of the sump 204, and back up throughanother part of the sterilising filter 214 located in the second region204 c of the sump 204 to the weir 206 a. Therefore, the partition 212forces the water to follow a convoluted path from the filter inlet 202to the weir 206 a. In this embodiment, the convoluted path is in theform of a U-shaped path. If the partition 212 were not present, thenwater entering the sump 204 would tend to flow over the weir 206 awithout passing through the sterilising filter 214, and sterilisationwould not take place.

The excess water, now sterilised, spills over the weir 206 a (arrow E)and flows down the filter outlet 208. The water collects at the base 100a of the collector 100 which is in communication with the piezo-electricdevice 102. The piezo-electric device 102 is set to oscillate at apre-determined frequency and magnitude such that sufficient vibrationalenergy is imparted to water molecules on the surface of the water in thecollector 100 to overcome surface tension effects. Therefore, the wateris turned into a fine mist in the interior space of the collector 100.

The fan 104 directs an airflow downwardly into the collector 100. Thisdirects the fine mist towards, and down, the exhaust conduit 37 whichleads to the outside of the outer case 12. This process continues untilall the water contained within the collector 100 is efficiently andhygienically removed from the collector 100.

FIGS. 5 a and 5 b illustrate the removal of the liquid treatment module30 from the outer case 12 for maintenance or replacement. The liquidtreatment module 30 is removed downwardly from the hand dryer 10. Inthis embodiment, the filter 200 forms part of the liquid treatmentmodule 30 and is removable from the outer case 12 with the liquidtreatment module 30.

It will be understood that the invention is not to be limited to theprecise details described above. Other variations and modifications willbe apparent to the skilled reader.

For example, the drying apparatus need not take the form of a handdryer. The drying apparatus could be a condenser-type laundry dryer. Insuch a laundry dryer, water evaporated from wet textiles in the drum(cavity) of the laundry dryer can be condensed, filtered by a filtrationunit and then removed by agitation or evaporation.

Further, the invention could be utilized in other forms of dryingapparatus; for example, other forms of domestic or commercial dryingapparatus such as washer-dryers, ventilation-type laundry dryers orfull-length body dryers.

Additionally, other forms of liquid dispersion unit can be used todisperse the collected liquid; for example, an ultrasonic generator, afan, a heating element or electrolysing apparatus. Any of these devicescould be used in place of a piezo-electric device to agitate, evaporateor electrolyse the water (or other liquid) as required.

The liquid treatment module need not be located inside a chamber presentin the drying apparatus. Other arrangements are possible; for example,the module could form a part of the outer case, or could be mounted onor outside the outer case of the drying apparatus.

Further, the liquid treatment module need not be removed from the lowerpart of the drying apparatus. The liquid treatment module may form partof the upper side or top of the drying apparatus, and be removedsideways or upwardly depending upon the requirements of the dryingapparatus. Additionally, it need not be removable and could remain fixedinside the drying apparatus.

As a further variation, other forms of airflow generator are possible.For example, an air bleed or exhaust airflow could be taken from a motorunit. For example, the motor unit for driving the drying process of thehand dryer has a fan. This fan could be used to generate an airflow tovent the evaporated water to the outside of the drying apparatus ratherthan using an additional fan.

Additionally, the dimensions of the glass beads need not be 4 mm. Theymay be varied in size from 1 mm to 6 mm. Additionally, other types ofparticulate filter media could be used; for example, glass-fibrebrushes, plastic brushes, porous ceramics, plastic beads or smallstones. What is important is that the particulate filter is formed froman inert material with a density greater than 1 g/l. The size of theparticulate filter may be varied and may be any size suitable to ensurethat the majority of the particulates are filtered and removed from thewater to prevent the sterilising filter from clogging and becomingblocked.

As an additional variation, a number of particulate filters may beprovided. They may be located outside of the sump, for example in thefilter inlet to pre-filter water before it reaches the sump.

The sterilising filter need not be formed of a resin with substantiallyspherical particles with dimensions in the range of 0.1 to 2 mm. Otherparticle shapes or sizes could be used, for example by grinding.Alternatively, a single, porous block of resin could be used. Further,the sterilising filter need not be formed from a resin. Other inorganichost media could be used; for example, inorganic polymers, metalchelates, metal complexes or crystal structures.

The loading of iodine need not be 500 g/l and may be within a preferredrange of 300 g/l to 600 g/l. Further, the concentration of iodinereleased into the water may also be outside the range of 1 to 5 ppm.What is important is that the concentration is high enough to kill thebacteria in the water whilst low enough to avoid discolouring the water.Further, the volume of the sterilising filter can be varied, provided itis sufficient to sterilise the water.

Additionally, the anti-bacterial agent in the sterilising filter neednot be iodine and could include alternative bacteria-killing media; forexample, a halogen-containing material or a precursor to ahalogen-containing material. Typical, non-exhaustive, examples of theseare materials including: Chlorine, Bromine, Iodine, Hypochlorite orHypobromide. Alternatively, other methods of sterilising bacteria may beimplemented; for example, Titanium dioxide or UV-radiation activatedsilver nanoparticles.

Further, the particulate filter and sterilising filter need not belocated wholly in the sump. They could be located above the sump, out ofthe water in the sump, or partially submerged in the water in the sump.

As a further variation, the particulate-filtering media and thebacteria-killing media need not form separate stages in the filter andmay be combined to form a single unit.

As a further variation, the filter need not be removable from the dryingapparatus. The filter could remain inside the casing of the dryingapparatus when the liquid treatment module is removed. The filter couldeither be removable separately from the liquid treatment module or befixed permanently inside the casing of the drying apparatus.

1. A drying apparatus comprising an outer case, a portion of the outercase defining a cavity in which articles can be dried, an outletdisposed at the lower end of the cavity and a filter unit arrangeddownstream of the outlet, wherein the filter unit comprises aparticulate filter and a sterilising filter.
 2. The drying apparatusaccording to claim 1, wherein the sterilising filter is locateddownstream of the particulate filter.
 3. The drying apparatus accordingto claim 1 or 2, wherein the filter unit further comprises a filterinlet, a filter outlet and a sump having a maximum level of liquid. 4.The drying apparatus according to claim 3, wherein the sterilisingfilter is located in the sump.
 5. The drying apparatus according toclaim 4, wherein the sterilising filter is located below the maximumlevel of liquid.
 6. The drying apparatus according to claim 3, whereinthe particulate filter is located in the sump.
 7. The drying apparatusaccording to claim 6, wherein the particulate filter is located belowthe maximum level of liquid.
 8. The drying apparatus according to claim3, wherein the filter outlet includes a portion which determines themaximum level of liquid.
 9. The drying apparatus according to claim 3,wherein the filter unit further comprises a flow directing guide guidingliquid through the filter unit.
 10. The drying apparatus according toclaim 9, wherein the flow directing guide comprises a partition forguiding liquid through the filter unit.
 11. The drying apparatusaccording to claim 10, wherein the partition defines a convoluted pathfrom the filter inlet to the filter outlet.
 12. The drying apparatusaccording to claim 11, wherein a part of the partition located withinthe sump is arranged to guide the liquid along a U-shaped path.
 13. Thedrying apparatus according to claim 9, wherein the partition is arrangedto separate at least a part of the sterilising filter.
 14. The dryingapparatus according to claim 3, wherein the sterilising filter comprisesa material including an anti-bacterial agent.
 15. The drying apparatusaccording to claim 14, wherein the material is a resin.
 16. The dryingapparatus according to claim 15, wherein the resin comprises particleshaving a dimension of at least 0.1 mm.
 17. The drying apparatusaccording to claim 15, wherein the resin comprises particles having adimension no more than 2 mm.
 18. The drying apparatus according to claim14, wherein the anti-bacterial agent comprises a halogen-containingmaterial or a precursor to a halogen-containing material.
 19. The dryingapparatus according to claim 18, wherein the halogen-containing materialincludes a component selected from the group consisting of Chlorine,Bromine, Iodine, Hypochlorite and Hypobromide.
 20. The drying apparatusaccording to claim 14, wherein the resin is arranged to release theanti-bacterial agent into the liquid at a concentration of at least 1ppm.
 21. The drying apparatus according to claim 14, wherein the resinis arranged to release the anti-bacterial agent into the liquid at aconcentration no greater than 5 ppm.
 22. The drying apparatus accordingto claim 1, wherein the particulate filter comprises a layer of beads.23. The drying apparatus according to claim 22, wherein the diameter ofthe beads is at least 1 mm.
 24. The drying apparatus according to claim23, wherein the diameter of the beads is no more than 6 mm.
 25. Thedrying apparatus according to claim 1, wherein the filter unit formspart of a liquid treatment module which is removable from the dryingapparatus.
 26. The drying apparatus according to claim 25, wherein theliquid treatment module further comprises a liquid dispersal unitincluding a collector located downstream of the filter unit and anevaporation unit in communication with the collector for evaporatingliquid collected therein.
 27. The drying apparatus according to claim26, wherein the evaporation unit is a high frequency agitator.
 28. Thedrying apparatus according to claim 1, wherein the drying apparatus is ahand dryer and the cavity is dimensioned to receive a user's hands. 29.(canceled)